Convert floating-point MDCT coefficients to 24-bit fixed-point all at once

instead of doing it separately in 2 different functions.
This makes float AC-3 encoding approx. 3-7% faster overall.
Also, the coefficient conversion can now be easily SIMD-optimized.

Originally committed as revision 26232 to svn://svn.ffmpeg.org/ffmpeg/trunk

1 files changed, 11 insertions, 0 deletions

diff --git a/libavcodec/ac3enc_fixed.c b/libavcodec/ac3enc_fixed.c
index 9d3b195ded..3723b08b96 100644
--- a/libavcodec/ac3enc_fixed.c
+++ b/libavcodec/ac3enc_fixed.c
@@ -319,6 +319,17 @@ static int normalize_samples(AC3EncodeContext *s)
 }
 
 
+/**
+ * Scale MDCT coefficients from float to fixed-point.
+ */
+static void scale_coefficients(AC3EncodeContext *s)
+{
+    /* scaling/conversion is obviously not needed for the fixed-point encoder
+       since the coefficients are already fixed-point. */
+    return;
+}
+
+
 #ifdef TEST
 /*************************************************************************/
 /* TEST */